FIG. 6 is a cross-sectional view showing a portion of a conventional pneumatic tire 2. The tire 2 includes a tread 4, sidewalls 6, a carcass 8, a belt 10, and a liner 12.
The liner 12 is located inward of the carcass 8. The liner 12 is joined to the inner peripheral surface of the carcass 8. The liner 12 includes a first inner liner 14 and a second inner liner 16. The first inner liner 14 forms an inner portion of the liner 12. The second inner liner 16 is located between the first inner liner 14 and the carcass 8.
The first inner liner 14 is obtained by crosslinking a first rubber composition. The principal component of the base rubber of the first rubber composition is generally isobutylene-isoprene-rubber. The first inner liner 14 is excellent in air blocking property. The first inner liner 14 serves to maintain the internal pressure of the tire 2.
The second inner liner 16 is obtained by crosslinking a second rubber composition. The principal component of the base rubber of the second rubber composition is generally natural rubber. The second inner liner 16 serves to join the first inner liner 14 to the inner peripheral surface of the carcass 8. In addition, the second inner liner 16 prevents the first inner liner 14 from directly contacting with cords included in the carcass 8. Thus, occurrence of cord loose is prevented.
In light of weight reduction of the tire 2, the configuration of the liner 12 has been variously examined. Examples of such examination are disclosed in JP2002-178714 and JP2008-30575.
FIG. 7 shows a conventional tire 18 different from the tire 2 shown in FIG. 6. The tire 18 includes a tread 20, sidewalls 22, a carcass 24, a belt 26, and a liner 28. The tire 18 has the same configuration as that of the tire 2 shown in FIG. 6, except for the liner 28.
In the tire 18, the liner 28 includes a pair of first inner liners 30 arranged so as to be spaced apart from each other in the axial direction; and a second inner liner 32 joined to the inner peripheral surface of the carcass 24. Similarly to the tire 18 shown in FIG. 6, the first inner liners 30 serve to maintain the internal pressure of the tire 18. The second inner liner 32 serves to join the first inner liners 30 to the inner peripheral surface of the carcass 24.
In the tire 18, the first inner liners 30 are not provided at an equator portion thereof. The tire 18 is lighter than the tire 2 shown in FIG. 6. The first inner liners 30 in which a middle portion is removed can contribute to weight reduction of the tire 18.